PHOSPHORANEIMINATO COMPLEXES OF BORON - SYNTHESES AND CRYSTAL-STRUCTURES OF [BBR2(NPME3)](2), [B2BR3((NPPR3)-PR-I)(2)]BR, [B-2(NPET3)(4)]BR-2, [B2BR2(NPPH3)(3)]BBR4 AND [(B-2(NME2)(2))(2)(NPET3)(2)]CL-2

The bromoderivatives of the title compounds are prepared from the corr esponding silylated phosphoraneimines Me3SiNPR3 and boron tribromide. The boron subcompound [{B-2(NMe2)(2)}(2)(NPEt3)(2)] Cl-2 derives from Me3SiNPEt3 and B2Cl2(NMe2)(2). All complexes are characterized by NMR and IR spectroscopy as well as by crystal structure determinations. [B Br2(NPMe3)](2) (1): Space group P2(1)/n, Z = 2, R = 0.031. Lattice dim ensions at -50 degrees C: a = 723.8, b = 894.2,c = 1305.4 pm, beta = 9 2.35 degrees. 1 forms centrosymmetric molecules in which the boron ato ms are linked via mu(2)-N bridges of the NPMe3- groups to form B2N2 fo ur-membered rings with BN distances of 149.9 and 150.9 pm. [B2Br3((NPP r3)-Pr-i)(2)]Br (2): Space group P2(1), Z = 2, R = 0.059. Lattice dime nsions at -80 degrees C: a = 817.6, b = 2195.7, c = 851.5 pm, beta = 1 15.09 degrees. In the cations of 2 the boron atoms are linked via the mu(2)-N atoms of the (NPPr3-)-Pr-i groups to form planar, asymmetric B 2N2 four-membered rings with B-N distances of 143 and 156 pm. [B-2(NPE T3)(4)]Br-2 . 4 CH2Cl2 (3): Space group C2/c, Z = 4, R = 0.042. Lattic e dimensions at -50 degrees C: n = 1946.1, b = 1180.3, c = 2311.3 pm, beta = 101.02 degrees. The structure contains centrosymmetric dication s in which both the boron atoms are linked by the N atoms of two of th e NPEt3- groups to form a B2N2 four-membered ring with B-N distances o f 149.6 pm. The remaining two NPEt3- groups are terminally bonded with very short B-N distances of 133.5 pm. [B2Br2(NPPh3)(3)]BBr4 (4): Spac e group P (1) over bar, Z = 2, R = 0.065. Lattice dimensions at -50 de grees C: a = 1025.7, b = 1496.1, c = 1807.0 pm, alpha = 85.09 degrees, beta = 82.90 degrees, gamma = 82.72 degrees. In the cation the boron atoms are linked via the mu(2)-N atoms of two of the NPPh3- groups to form a nearly planar B2N2 four-membered ring with B-N distances of 149 .3-153.1 pm. The third NPPh3- group is terminally connected with the s p(2) hybridized boron atom and with a B-N distance of 134.1 pm along w ith an almost linear BNP bond angle of 173.6 degrees. [{B-2(MMe2)(2)}( 2)(NPEt3)(2)]Cl-2 . 3 CH2Cl2 (5): Space group C2/c, Z = 4, R = 0.098. Lattice dimensions at -70 degrees C: a = 1557.9, b = 1294.7, c = 2122. 9 pm, beta = 96.08 degrees. The structure of 4 contains centrosymmetri c dications in which two by two B-B dumb-bells are linked via the mu(2 )-N atoms of the two NPEt3- groups to form B4N2 six-membered rings wit h B-N distances of 150 and 156 pm and B-B distances of 173 pm. The B-N distances of the terminally bonded NMe2- groups correspond to 138 pm double bonds.